Dehydrative Formation of Isosorbide from Sorbitol over Poly(ionic liquid)–Covalent Organic Framework Hybrids

In this study, the covalent bonding of linear poly(ionic liquid)s (PILs) with covalent organic frameworks (COFs) was accessed by copolymerization of a vinyl-decorated COF with 4-vinylbenzyl chloride, followed by quaternization with tertiary amines. The resultant PIL-COF composite by anchoring a proper content of vinyl sites on the COF-based comonomer retains the crystallinity and porosity, thereby facilitating access of the reactants to the catalytic active sites. As a proof of concept, the dehydrative transformation of sorbitol into isosorbide was selected as a benchmark reaction, whose rate improved significantly in the presence of PIL-COF-0.33 compared with those of individual components and the mesoporous PIL counterpart due to uniform pore sizes and flexible linear catalytic chains. In addition, the hybrids bearing a chemical cross-linkage between PILs and COFs are robust, and PIL-COF-0.33 can be recovered and reused for 10 runs without significant reactivity loss. These findings provide the basis for a novel design concept for achieving both efficient and stable IL catalysis.